Troldesh

Troldesh is ransomware — a malware that demands a payment in order to unlock encrypted files. It is also can search and steal information from the banking programs if such are found on the infected machine.

Type
Ransomware
Origin
Unknown
First seen
1 January, 2014
Last seen
9 October, 2021
Also known as
Encoder.858
Global rank
23
Week rank
40
Month rank
24
IOCs
690

What is Troldesh ransomware?

Troldesh, also know as Encoder.858 is ransomware belonging to the Shade ransomware family. It was created in 2014. The malware encrypts files on the victim’s machine and demands a ransom for the data to be restored.

Attempting to get as much information as possible the malware also scans the target PC for banking files or banking programs, in an effort to squeeze every last penny.

General description of Troldesh

Attacking Windows users mainly in Russia, Ukraine, and Germany, Troldesh is one of the three most commonly used encryption software in Russia.

In addition to this behavior, Troldesh ransomware often comes in conjunction with two particular malware samples, namely Mexar, and Teamspy, which allows attackers to control the victim's PC remotely and gives the virus the ability to install other malware including trojans on the infecting PC.

In fact, unlike most other ransomware, this virus does not stop executing after encrypting the victim’s files but instead starts an infinite loop where it requests URLs of other malicious programs from the command server, downloading and installing them on a contaminated machine. This means that most victims contaminated with Troldesh, in fact, may end up with a whole host of infections on their PC. And even with removal tools and decryptors, it can be challenging to get rid of this issue.

Even though the malware itself has not evolved a lot throughout its lifespan, the method which attackers use to demand the ransom has changed. The first malware samples used to provide an email address at which the victim could contact the hackers and negotiate the payment, whereas in newer campaigns ransom node demands victims to use the Tor browser in order to navigate to a payment page that is located on the Dark Web.

Being a part of the Shade family, Trodlesh shares several familiarities with related malware. As such, all members of the family are written in C++ and utilize CTL. Another shared feature is a static link with a Tor client. Every particular malware sample also has a hardcoded URL of the command server. Malicious programs of this family are also known to exhibit similar or identical behavior. As such, they create 10 identical ransom notes in two languages – Russian and English and name them README1.txt or README10.txt.

Troldesh malware analysis

A video simulation recorded on ANY.RUN allows us to examine the lifecycle of the Troldesh malware in a lot of detail.

process graph of a troldesh ransomware execution Figure 1: Process graph generated by ANY.RUN helps us visualize the life cycle of the virus

Troldesh execution process

Troldesh ransomware is spread in the form of a script file, either Javascript or JScript. Usually, these files are packed in an archive file, that is sometimes protected with a password. In the simulation performed on ANY.RUN, after a script file was unpacked and launched, it installed an executable file from the internet. It should be noted, that in the case of Troldesh, executable files normally have "not suspicious" extensions along with the likes of .jpg. After being downloaded, the files are renamed and executed.

As shown in the ANY.RUN simulation, after running, the file immediately began performing the malicious activity, namely: encrypting files, stealing personal data, deleting shadow copies, and changing autorun values in the registry. Files encrypted by the latest versions of Troldesh are known to have a .crypted000007 extension which was also the case in our simulation. Lastly, after encryption was completed the malicious executable file dropped ransomware instructions on the desktop.

process tree of a troldesh ransomware execution Figure 2: Process tree of a Troldesh ransomware execution

How to avoid infection by Troldesh?

Since Troldesh is commonly distributed using malspam campaigns that mimic real company newsletters, a good way of staying safe is thoroughly checking for the authenticity of emails before downloading any attachments. If necessary, one can get in touch with a company that is the presumable author of the newsletter and verify that they have, in fact, sent the email.

Once infected, Troldesh installs several secondary malware samples on the victim’s PC, thus after Troldesh removal – malware deletes itself from the PC, it is important to conduct a global system scan and make sure that one’s machine is not swarming with other viruses as well.

Distribution of Troldesh

Troldesh ransomware is known to utilize two main attack vectors – email spam and exploit kits. Malspam campaigns usually mimic legitimate information newsletters from real Russian companies, including banks and large supermarket chains. The emails themselves contain an archive file in which another script file is included.

Upon unpacking the archive and clicking on the file, a malicious loader is installed. It in turn downloads and installs the main payload – Troldesh itself. The loader is known to be stored on legitimate but compromised WordPress websites where it is hidden as an image file.

Troldesh is also known to utilize Axpergle and Nuclear exploit kits, and these attacks are, arguably, more dangerous than email spam as they don’t require active actions from the user for the contamination process to begin. Instead, upon visiting a compromised URL, which can be a website hosted by the attackers or a legitimate website that has been hacked, the malware utilizes a vulnerability either in the browser itself or in one of the browser plugins, successfully penetrating into the users PC and starting the execution automatically. Thus, victims can get infected without ever realizing the danger, so get a removal program and a decryptor.

Communication with C&C

Address information of C&C servers is embedded in the body of each malware sample. Servers themselves are hosted on the dark web and communication is established with the use of a Tor client.

Once installed on a victim's PC, the malware requests a public key value from the server to encrypt the victim’s files. Should the connection attempt fail, the virus uses one of one hundred private key values stored in its memory.

How to detect Troldesh using ANY.RUN?

Since Troldesh ransomware writes into the registry analysts can detect it by looking at registry keys. Choose the process by clicking on it in the process tree of the task then click on the "More info" button. In the "Advanced details of process" window switch to the "Registry changes" tab and take a closer look. If the analyzed sample writes a value "906D0F2E2F604F839E04" with the name "xi" into the key HKLM\SOFTWARE\System32\Configuration it's Troldesh.

Registry changes created by Troldesh Figure 3: Registry changes created by Troldesh

Conclusion

Troldesh is an extremely dangerous ransomware that is able to contaminate victims who simply end up browsing to the wrong place at the wrong time, ending up on a website hacked by the attackers. Unlike much other ransomware that simply demands money in exchange for user’s encrypted data, Troldesh doesn’t stop there and goes the extra mile to spread other dangerous malware samples on a victim’s PC.

Utilizing analysis services like ANY.RUN is a great way to examine the virus from a safe environment and develop a sufficient defense strategy.

P.S.

On the 27th of April, 2020 authors behind Troldesh ransomware announced that they stopped distribution of the ransomware and publish the decryption keys with a decryptor and instructions. They said that apologize to all the victims of the trojan and hope that the keys they published will help them to recover their data. You can take a look at the task in which their keys and tool were used to decrypt data.

IOCs

IP addresses
66.171.248.178
104.16.154.36
104.16.155.36
192.168.100.172
Hashes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isns.net
qxq.ddns.net
majul.com
elx01.knas.systems
e8960.b.akamaiedge.net
www.whatismyipaddress.com
www.whatsmyip.net
www.planiligue.com
hunterdekaron.net
bb-sandonato.com

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